How do I see all vertices in edit mode?
This is because of what modifiers are. They take the existing thing, and do a “last minute” operation before rendering it. This is great for deforming things in animations or doing a basic change (like beveling) that you may want to tweak much later without going through 32 Undos. The mesh’s actual data will not change unless you apply the modifier. You can turn on “show in edit mode” on the modifier header, but it will still have a ghost overlay of the actual mesh data you are working with.